Will 1842 mainspring fit an 1841 Mississippi?

[Niederlander]

Gentlemen, Does anyone here know if the 1842 Musket mainspring is the same as the 1841 Mississippi mainspring? They look the same in pictures but I have no way of checking it. Thanks!

[John Holland]

They are not interchangeable, among other things the arm on the M-1842 Musket spring is much too long for the M-1841 Rifle lock.

[Carolina Reb]

How about an Aston/Johnson M-1842 pistol mainspring interchanging with a Mississippi? They look awfully close.

[Muley Gil]

Which mainspring do you need? Is it for an original or for a reproduction? Do you have an old, broken spring that can be measured?

[williamslaybaugh]

Here is a comparison, closest to the ruler 1842, Mississippi, 1847/52 cadet, Aston.
56885689

[John Bly]

I think your only choice is to find an 1841 spring. The 1847/1851 cadet is close but it may be more difficult to find than a real Mississippi spring. The Rifle Shoppe has new castings but they need to be fitted and heat treated. I used to get the Rifle Shoppe castings in bulk and work them up and I've sold probably about 200 of them over the years but they won't give me a decent discount on a quantity any more. I've not done any for 6 or 7 years now and I don't have any left except for a spare or two for my rifles.

[Niederlander]

Reproductions are available, so I'll just get one of those. I wondered because 1842 springs seem to be everywhere and figured I could save some money. Thanks for the information, gentlemen!